The present invention relates to a semiconductor device, particularly a semiconductor device including: at least a film circuit which is manufactured by forming plural leads on an insulating layer serving as a base, setting one ends of the leads as semiconductor element side terminals to be connected to the electrodes of a semiconductor element and forming external terminals at the other ends of the leads, whereby the film circuit is provided with a element facing portion and an outside portion at the outside of the element facing portion; and a semiconductor element in which the respective electrodes are connected to the semiconductor element side terminals of the leads, and the surface of the semiconductor element is adhesively attached to the back surface of the element facing portion through an adhesive sheet, the gap between the film circuit and the semiconductor element being sealed, and a method of manufacturing the semiconductor device.
There have been developed various semiconductor devices in which each electrode of a semiconductor element is bonded to the tip of each lead of a film circuit, and the gap between the semiconductor element and the film circuit is sealed with resin, and FIGS. 1A and 1B show one of developed semiconductor devices, wherein FIG. 1A is a plan view and FIG. 1B is a cross-sectional view.
In FIGS. 1A and 1B, a represents a film circuit comprising a base b formed of polyimide tape or the like and leads c formed on the back surface of the base b, and the film circuit a has an element facing portion which is disposed so as to face a semiconductor element g as described later, and an outside portion e located at the outside of the element facing portion. f represents each soldering ball which is bonded to one end of each lead c, and it constitutes an external terminal of the semiconductor device.
g represents a semiconductor element, and each electrode thereof is bonded to a terminal of each lead c at the opposite side to the soldering ball side. h represents a cushioning adhesive sheet for adhesively attaching the back surface of the element facing portion d of the film circuit a and the surface of the semiconductor element g, and m represents a slit of the sheet h. i represents a ring of metal (copper, for example) which is connected to the lower surface of the peripheral edge portion of the outside portion e of the film circuit a, and it serves as an enforcing plate. If occasion demands, the ring is grounded to have an electrostatic shield effect, and thus it also serves to enhance resistance to noises. j represents resin which is filled to seal the gap between the film circuit a and the semiconductor device g.
The film circuit a having the element facing portion d and the outside portion (a portion which extends outwardly substantially from the semiconductor element, viewed from the lower side) e is used because the integration density of the semiconductor element g is enhanced and the number of electrodes is increased more remarkably as compared with the size thereof.
FIG. 2 is a cross-sectional view showing another developed semiconductor device. In this case, the semiconductor element g and the outside portion e of the film circuit a are supported by using a supporter k which is formed of metal such as aluminum or the like, or other materials. l represents an adhesive member for adhesively attaching the supporter k and the outside portion e. The supporter k formed of metal or the like is used to prevent the film circuit a from slacking at the peripheral edge portion.
The case shown in FIG. 1 has such a problem that the film circuit a slacks, sags or droops at the outside portion e thereof. The reason is as follows. Since the base of the film circuit a is formed of a resin tape of polyimide or the like which has a thickness of about several tens microns, the outside portion e thereof is liable to be bent due to the dead weight thereof and thus it is liable to be sealed by resin j in this state. If the film circuit a is sealed while it is bent (slacks), the soldering balls f are not uniform in height. Specifically, the soldering balls f at the outside portion e are lower in height than the soldering balls f at the element facing portion d. This problem, that is, the problem that so-called co-planarity of the soldering balls lacks necessarily disturbs a semiconductor device from being excellently mounted on a print board or the like, and thus this problem cannot be neglected.
The semiconductor device shown in FIG. 2 has been developed in order to avoid the above "co-planarity problem". In the semiconductor device, the semiconductor element g and the outside portion e of the film circuit a are firmly supported by the supporter k of metal of aluminum or the like.
Accordingly, it has been expected that the slacking, sagging and drooping at the outside portion e can be prevented. However, it is the actual situation that the expectation cannot be perfectly satisfied. This is because it is difficult to sufficiently enhance the precision in the positional relationship between the outer shape of the supporter k and each soldering ball f due to the restriction in enhancement of processing precision of the supporter k of metal such as aluminum or the like and thus it is difficult to make the co-planarity perfect.
However, it has a disadvantage that when the support k formed of metal is used, it induces such a risk that the weight of the semiconductor device itself is increased and a requirement of reducing the weight of electrical equipment using the semiconductor device cannot be satisfied. Therefore, it is not necessarily better to use the semiconductor device shown in FIG. 2.